MG TF Series User Manual

Section £;.13
( TIlE IGNlTIO~ FAlIJIPMENT---- - ----"-
Section (;.14
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MODIFIED DISTRIBUTOR FIXING
DISTRIBUTORS WITH" HIGH LIFT" CAMS
The contact breaker setting for the symmetriC and
asymmetric types is ·010 in. to ·012 in. (,25 mm. to
30 mm.) gap. and for the high-lift type is ·014 in. to
·016 in. (,36 mm. to ·41 mrn.).
Later models are fitted with a new type of distri-
butor. haVing hfgh-lift cams. Owing to the shape of
these cams the contact breaker gap must be set to
-014 in. to -016 in. (,36 mm. to ·41 mrn.). Previous
distributor cams were of two types-symmetric and
asymmetric, and both of these types necessitated a
contact breaker gap of ·010 in. to ·012 in. (·25 mm.
to ·30 mm.).
The wider gap of the high-lift cam. together with
the steep angle of the cam face, gives more accurate
ignition timing and controls pitting and piling action
which limits useful
contact life.
When setting contact gaps with the high-lift cam
more care is needed when checking that the fibre
heel is on the highest point of the cam rise, because
maximum
separation of the contact points is only
obtained over a small angular movement of the dis-
tri butor shaft.
All three types of cam are illustrated in Fig. C.20.
Apart from the appearance of the cams, distributors
fitted with high-lift cams can be Identified by reference
to the suffix letter which follows the Service No.
Distributors bearing the suffix "E" or any letter
subsequent to -" ~ .. after the Service No. 40162 are
fitted with high-11ft cams, and those with suffix r etters
previous to " E " are of the symmetr.ic or asymmetric
type.
HIGH LIFT
ASYMMETRIC
Fig. C.20.
The three types of distributor cam.
SYMMETRIC
Fig. C. \9.
The later type fhdng for the distributor. consisting of
a cotter bolt engagi ng the distributor body stem.
A new standardised method of distributor fixing
has
been Incorporated In all M.G. Midget (Series
.. TD") cars, commencing at Engine No. XPAG/
TD2/20942, and all Series" TF " cars.
The mod lfled fixing consists of a tapered cotter
bolt passing through the distributor housing boss in
the cylinder block and contacting the stem of the
distributor; and it replaces the split adjusting clip
hitherto employed.
Distributors using the cotter pin attachment are
released by slackening the cotter bolt inwards to free
its tapered surface from the stem of the distributor.
While the location of the distributor rotor will not
be disturbed owing to the action of the offset driving
tongue. release of the distributor body and stem will
affect
the ignition point, and it is therefore essential
to
mark the distributor body and the face of its housing
before removal
to ensure correct ignition timing on
replacement. The distributor housing face is marked
with a scale to facilitate this.
C.12
M.G. Midget. Issue 3 (H & E) 82966-1/51
Wishvilles Classic
Automobile Library

MG TF Series Specifications

General

Brand	MG
Model	TF Series
Category	Automobile
Language	English